Many semiconductor devices utilize bond pads as the terminals for electrically connecting active circuits in the device to an external circuit. The bond pads are select areas of the interconnect wiring pattern left exposed after formation of the passivation layer which covers the semiconductor die. The active circuits in the die are connected to the interconnect wiring and accessed through the bond pads. Thin wires are bonded to the bond pads. These bond wires electrically connect the bond pads to metal leads which, after the die/lead assembly has been enclosed within a sealed package, are inserted into or otherwise attached to a printed circuit board.
During the wire bonding process, a heat block heats the die and the leads to a temperature of about 150° C. to 350° C. The end of the bond wire is heated by an electrical discharge or a hydrogen torch to a molten state, thus forming a ball of molten metal on the end of the bond wire. The molten ball is pressed by a bonding capillary tool against the heated bond pad, sometimes in combination with ultrasonic vibration, to alloy the metallic elements of the wire and the metal bond pad and thereby bond the wire to the pad. The bonding capillary tool is then moved to a bonding site on the appropriate lead. The wire is pressed against the heated lead to bond the wire to the lead. The bond wire is then tensioned and sheared. The process is repeated for each bond pad on the die.
The bonding surface of conventional bond pads is substantially flat. The present invention is directed in general to an improved bond pad and, more specifically, to a bond pad having openings formed in the bonding surface of the bond pad. It is believed that forming openings in the bonding surface of the bond pad may, in some instances, improve the strength of the wire bond.